SkyOffsetFrame#
- class astropy.coordinates.SkyOffsetFrame(*args, **kwargs)[source]#
Bases:
BaseCoordinateFrame
A frame which is relative to some specific position and oriented to match its frame.
SkyOffsetFrames always have component names for spherical coordinates of
lon
/lat
, not the component names for the frame oforigin
.This is useful for calculating offsets and dithers in the frame of the sky relative to an arbitrary position. Coordinates in this frame are both centered on the position specified by the
origin
coordinate, and they are oriented in the same manner as theorigin
frame. E.g., iforigin
isICRS
, this object’slat
will be pointed in the direction of Dec, whilelon
will point in the direction of RA.For more on skyoffset frames, see “Sky Offset” Frames.
- Parameters:
- representation
BaseRepresentation
orNone
A representation object or None to have no data (or use the other keywords)
- originastropy:coordinate-like
The coordinate which specifies the origin of this frame. Note that this origin is used purely for on-sky location/rotation. It can have a
distance
but it will not be used by thisSkyOffsetFrame
.- rotationastropy:angle-like
The final rotation of the frame about the
origin
. The sign of the rotation is the left-hand rule. That is, an object at a particular position angle in the un-rotated system will be sent to the positive latitude (z) direction in the final frame.
- representation
Notes
SkyOffsetFrame
is a factory class. That is, the objects that it yields are not actually objects of classSkyOffsetFrame
. Instead, distinct classes are created on-the-fly for whatever the frame class is oforigin
.Attributes Summary
Default representation for differential data (e.g., velocity)
Default representation for position data
Mapping for frame-specific component names
The origin of the offset frame
The rotation angle for the frame orientation
Methods Summary
represent_as
(base[, s, in_frame_units])Ensure the wrap angle for any spherical representations.
Attributes Documentation
- default_differential#
Default representation for differential data (e.g., velocity)
- default_representation#
Default representation for position data
- frame_attributes = {'origin': <astropy.coordinates.attributes.CoordinateAttribute object>, 'rotation': <astropy.coordinates.attributes.QuantityAttribute object>}#
- frame_specific_representation_info#
Mapping for frame-specific component names
- name = 'skyoffsetframe'#
- origin#
The origin of the offset frame
No default value
- rotation#
The rotation angle for the frame orientation
Default: 0.0 deg
Methods Documentation